Verbio says it is a leading manufacturer in the German biomethane and biofuels market running four production facilities producing around 27 million gallons of renewable natural gas, 140 million gallons of biodiesel and 87 million gallons of ethanol each year.

The corn cobs, husks and stalks create a huge fire liability for the city and county.

Northrup said all stover stockpiles "will continue to be monitored and managed to minimize risk."

Even though DuPont closed the plant, Monte Shaw, executive director of the Iowa Renewable Fuels Association, said interest remains strong for renewable fuels.

"Oil prices are headed back up and more states are enacting low-carbon policies, so I think there is a future for low-carbon transportation fuels — everything from corn ethanol to biodiesel to cellulosic ethanol," Shaw said.

"I’m excited that they found a buyer for the facility and that it’s still going to be in the renewable transportation fuels sector," he said.